Mobile telephones and similar communication devices are rapidly expanding in functionality. In addition to basic voice communication, such devices are today providing text messaging, internet access, e-mail (with access to attached files), personal information management, document creation, digital photography and videography, and downloading, storage, and delivery of audio and video content.
To accomplish such a variety of functions, there is a need to provide keyboards (keyed or touch-screen based) for the input of commands and data, and display screens capable of presenting a considerable amount of information. This has proved to be a challenge, given the small screen area available in a hand-held device. Full-function keyboards, such as the standard QWERTY array of keys and buttons, are difficult to provide while maintaining the convenient size consumers expect of a mobile device. The addition of other functional elements, such as displays, cameras, memory modules, and dedicated control buttons and connectors for these elements, only adds to the challenge, as does the need to house a battery capable of powering all of these elements. Due in part to the conventional wisdom in the industry that “thinner is better”, prior art solutions have relied on the relentless miniaturization of increasingly complex digital electronic components. As the cost and difficulty of such miniaturization are approaching practical limits, there is a need for alternative designs.
There are many commercially available devices that incorporate hidden functional elements, such as keypads, via hinged “clamshell” designs, generally having a pivoting display that flips up from a base structure containing a keypad. Another class of devices employs slide-out keypads. There are also single-screen devices, such as the Apple iPhone™, where the keypad and almost all control buttons are software-generated, and displayed as needed on a touch-sensitive screen. These designs provide a limited screen area, and the user is generally limited to the display of only one type of data, or the output of one application, at any given time. In particular, the large area claimed by a virtual keyboard leaves relatively little display area for other purposes, and much of that remaining area must be dedicated to a display of the text being entered via the keyboard. There remains a need for portable communication devices that permit the user to view multiple types of data, from multiple applications, at one time. Multi-screen designs have been put forth in order to address this need, but have not been accepted in the marketplace. Kawamura (U.S. Pat. No. 7,496,378), for example, provides a supplementary fold-out display screen grafted onto a clamshell form cell phone. The design is thick and blocky, the extra screen that folds out to the side unbalances the device, and there is no provision for multifunctional hardware.